docs: def _norm_cmap(values, cmap, normalize, cm, vmin=None, vmax=None):
      """
      Normalize and set colormap. Taken from geopandas@0.2.1 codebase, removed in geopandas@0.3.0.
      """
  
      mn = min(values) if vmin is None else vmin
      mx = max(values) if vmax is None else vmax
      norm = normalize(vmin=mn, vmax=mx)
      n_cmap = cm.ScalarMappable(norm=norm, cmap=cmap)
      return n_cmap